Trouble adding fuel with Predator

[rueljr]

I've had my Predator since November and have dynoed my car numerous times . My car has always been about 1 point to lean (13 A/F) as I've done the mods and changed tunes. I started with the Predator performance tune when the car was still stock and tried to add more fuel because it was a little lean, but the A/F never changed. Later, I added a pulley, CAI intake, catback, and the Predator pulley tune. As usual, the A/F was a little lean, so I added max fuel and again no change to the A/F. I added a ported Apten and two different custom Predator tunes from two different tuners. Both custom tunes were lean, and again, I added max fuel with the Predator. Surprise, the A/F never changed. I have never been able to change the A/F with the Predator. Has anyone else had a similar problem with the Predator?

 

[JPKII]

Your HP/TQ numbers look like Dynojet numbers so I'll assume that. Where was your A/F reading taken? Bung in X/H pipe or tailpipe? At what RPM are you seeing it go lean? When you are seeing the lean condition are you at 80% ++ throttle (WOT)?

 

[rueljr]

Yep, it was a Dynojet with a tailpipe sniffer. The custom tunes were flat, like most custom tunes, just at least 1 full point to lean (13.0 A/F or higher). The various Predator tunes were typical Predator tunes in that they start out very lean (14-15 A/F) then richen up to 13.0 by 4K and stay that way pretty much up to redline.

 

[JPKII]

I am not a dyno expert but I have heard that at lower RPMs the tailpipe sniffers on low displacement engines, like ours, aren't the most accurate. That may account for some of your problem at low RPMs. I would try a different dyno with a bung in your H/X pipe. A few weeks ago someone posted a study about this on SVTP. But with the search function down good luck trying to find it.

But even at higher RPM not seeing a difference I am not sure about that. Make sure you are going the right direction with the Predator as adding fuel means moving the pointer to the negative side. Also, and this is a long shot, make sure your dyno operator is mashing the pedal to the floor (maybe even datalog a run with your predator and see that you are getting above 80% or 4.0 Volts on your TPS). The reason I say this is because below that point the PCM monitors your front O2 sensors and runs the car closed loop to maintain 14.7. Once above 80% throttle the PCM converts to the WOT fuel and spark look up tables and I believe the Predator only changes the WOT tables.

Again I am not an expert, this is what I have learned from my own experiences in the past. I may be totally wrong. Maybe someone else could confirm what I said.

 

[n0xlf]

Might be worth putting the factory tune back in, resetting the tables on the Predator, and then loading your custom tune... Maybe something went wrong somewhere with the flashing process...I use the same dyno as you, and was able to richen up my tune, which showed on the AF...I posted it here, but since the search is down, who knows where it is..

Also, what factory flash are you running? YDH1 here...

 

[rueljr]

I data log all my dyno runs with an Autotap. All runs are in the open mode with 93% TPS and 100% load. The computer code is YDH1. I have put the stock tune back in and reset the Predator before and still can't change the A/F ratio. I've talk to James at RWTD, and he assured me that there was nothing wrong with the my Predator, but I'm starting to have my doubts.

 

[03SVTVA]

If the A/F is checked at the tailpipe you will definitely read leaner. The only way to get an acurate reading is to have a bung welded in before the cats.